Membranes such as yacht sails are usually provided with an eyelet or D-Ring that is used as a connector to allow the sail to be fastened in some way. One example is the clew of a headsail which will usually have an eyelet or grommet known as a clew ring. The clew ring allows the clew to be connected to a sheet in order to control or secure the sail.
Eyelets and D-Rings have the disadvantage that snap shackles or knots are usually required to establish a connection to the membrane, and these can fail. When snap shackles or similar connectors are used to connect a sail to sheets, the shackles are often taped to reduce the risk of failure. This is difficult and time consuming. Membranes such as sails and awnings are frequently required to be taken down and changed or reset, so slow or unwieldy connection methods such as knots can cause problems. Also, particularly when used to fasten a sail, snap shackles or knots can snag on shrouds or other fittings, and damage the fittings.